Blow molding apparatus

ABSTRACT

A reheat blow molding machine has an improved article handling system that carries heated preforms by a carriage assembly from an oven to a roller chain conveyor which moves them to a blow mold from whence the blown product is moved to an eject station. The motions are linear and cyclical or periodic, drive means for such intermittent motions being provided. Preforms are handled in groups of four, each one being supported by its capping ring in a locating notch on the carriage and by the finish groove in a holder notch above it when it is transferred to the conveyor. All notches are open on the side facing the oven and have self-centering features to get and keep alignment for transfer and positioning at the blow mold. The carriage which moves preforms horizontally toward the conveyor and raises them to the elevation for transfer to the holder notches of the conveyor. Transfer happens when the carriage passes underneath the conveyor whereupon the holder notches of the conveyor engage the preform grooves and sweep or wipe the preforms out of the open side of the carriage notches. The conveyor roller chain moves linearly at right angles to the carriage path and delivers correctly aligned group of preforms to a corresponding group of blow molds. The chain is on its side, i.e. with pins vertical, the holder notches are supported by chain lugs outward of the chain on a leaf spring, and sliding bearing means extend horizontally out from the chain to engage tracks which provide vertical support on the straight runs. At the blow station, the center rod passes through the stuffer cylinder rod and stuffer nose in a fluid-tight telescoping relation. At the ejection station, vertical guides provide position control over the product when the latter is pushed out of the conveyor holder notches whereby the product keeps a vertical alignment and falls away on a predetermined axis.

This is a division of application Ser. No. 869,499 filed June 2, 1986.

The present invention relates to an improvement in plastic blow moldingapparatus. One aspect is a conveyor system for handling an elongatedarticle--or plurality thereof--that depend from a part of the system.One aspect is an improvement in a preform handling system for a reheatblow molding apparatus to move one or more injection molded plasticresin preforms from an oven to a blow mold and to remove the blownproduct from the blow mold in connection with which the invention willbe described without intending to be limited thereto.

Blow molding is used in the art of manufacturing hollow articles such asbottles and jars from various plastics and resins such as polyethylene,polyvinyl chloride, polyacrylonitrile, polyethylene terephthalate andthe like.

In reheat blow molding, the plastic is first injection molded to make apreform. Later on, in a separate operation, the preform is reheated to asuitable temperature and is then blown into a product. The temperatureis selected to provide biaxial orientation of the end product, commonlya soft drink bottle. Where the end product is to be, for example, abottle with a threaded neck, the injection molding yields the advantagesof reducing thermal memory problems and providing a threaded neck whichwill not change significantly in shape or dimension during furtherprocessing.

The present invention is adapted to handle an article for blow moldingin the form of an injection molded hollow preform of such resin which inturn is shaped like a test tube that has external threads about is openend or finish. The body of the preform has been heated to an orientingtemperature but the threaded end (finish) has been kept cool, unheatedbecause such end is not to be blown. Typically, such a preform has atamperproof ring at the bottom of the threads and a stacking ring(sometimes called capping ring) underneath the tamperproof ring: theaxial space between these rings typically defines a groove and ispreferably the portion of the preform engaged by the conveyor of thepresent invention.

Blow molding apparatus of the sort to which the present invention ispreferably applied and of which it is an improvement is the CincinnatiMilacron RHB-V heat blow molding machine which has been in use for wellover a decade. Such machine (or components) is described in a number ofU.S. patents, among them U.S. Pat. Nos. 3,958,685; 4,082,175; (bothteaching couplings, conveyors suitable for ovens and ovens) and4,185,812 (blow molding pallet for use at a blow mold work station)which are expressly incorporated by reference herein.

The system of the present invention, while generally applicable toarticle handling, is preferably adapted to blow molding and mostpreferably is intended to replace the pallet assembly described in '812and also to provide as a component an improved novel means to transferthereinto heated preforms from a reheat oven or other source (e.g. like'685 or '175).

One object of the present invention is provision of an improved meansfor transporting a workpiece from a first station where received in themeans through a number of stations. Another object of the presentinvention is provision of an improved conveyor system for handling oneor more elongated depending workpieces. An object of the invention is toprovide a handling system for a reheat blow molding apparatus to moveone or more injection molded plastic resin preforms from an oven to ablow mold and to remove the blown product from the blow mold.

The invention thus includes a reheat blow molding apparatus to move aheated preform from an oven to a blow mold where it is blown into ahollow product using a stuffer assembly and to convey such product to aneject station wherein the preform has an unblown finish having at itslower end a capping ring from which depends a hollow tubular body thatis blown to form the product and a groove immediately above said cappingring, the ring and groove acting as locating means, and the remainder ofthe finish being above said groove. Further, the invention comprehends ablow molding machine with an oven section; a blow mold section for blowmolding the preform into a hollow product and ejecting such product fromthe machine; a preform transfer station, a blow station, a blow mold atsaid blow station, and a product eject station disposed linearly alongone side of said blow section; a carriage means for receiving a preformfrom the oven and moving same to the preform transfer station; anendless conveyor drive member (such as a roller chain) in said blow moldsection disposed in a horizontal plane (with the pins vertical if achain) and with a straight run extending along said blow section oneside; a plurality of outward facing preform holder means (each to engagea preform by the groove) spaced at a predetermined interval from eachother along said conveyor such that a holder means is at each of saidstations at the same time; and said carriage means having a fail safestructure to remove any accidentially retained preform prior to loadingat the oven.

One aspect of the invention relates to conveyor apparatus for conveyinga plurality of preforms (each preform being engaged by a conveyor holderat a groove between the capping and support rings on the upper end) froma transfer or loading station through a blowing station where eachpreform is received in a blow mold and converted to an expanded hollowproduct therein, and then to an ejact station where such product isejected, which apparatus indcludes roller chain disposed in a horizontalplane with its pins vertical and about sprockets; a plurality of groupsof preform holder assemblies arranged in succession on said chain, thepreform holder assemblies in each group being spaced the same as theblow molds are spaced so the preforms may be presented aligned withrespective blow molds; and an intermittent drive means to periodicallymove the chain an amount to remove an entire group of holder assemblies(with --when operating--products from said blow molds) to the ejectstation and to replace same with the next succeeding group of holders.Another aspect in such a conveyor wherein each holder assembly has aresilient member with an inner end and an outer end supported at itsinner end from the bottom pin link plate of the chain with the other endextending outboard of the chain pitch line; and a holder means on theresilient member outer end having a notch therein to receive and snuglyfit the preform groove, such notch being located to dispose the preformin alignment with its respective blow mold; and guide means for urgingeach preform fully into its holder notch thereby to acquire and keeppredetermined location.

The present invention also includes improvements of the stuffer andejector. The instant stuffer establishes a face seal relation with thepreform enabled by resilient support of the preform by the conveyor andalso (when equipped with a center rod) uses a hollow stuffer rod with atelescoping relation between stuffer and center rods with a lot lessmass to move than heretofore. The ejector drops the product straightdown and keeps the orientation straight up and down, thus simplifyingthe chore of product removal due to reliably keeping a pre-selectedorientation during ejection.

Other objects advantages and features will become apparent from thefollowing detailed description when read in conjunction with the annexeddrawings wherein:

FIG. 1 is a partially cutaway front elevation of a reheat blow moldingmachine equipped with the invention and generally depicting the ovendischarge and blow molding portion of the machine;

FIG. 2 is a side elevation as from 2--2 of FIG. 1;

FIGS. 3 and 4 are enlarged side elevation views showing successivepositions of the carriage assembly (reach and take assembly) outer ortop plate, preform, and oven coupling during reception at the ovendischarge;

FIG. 5 is a top view on section 5--5 of FIG. 4;

FIG. 6 is a section on 6--6 of FIG. 4;

FIGS. 7 and 8 are side elevation views on section 7--7 of the FIG. 1carrier assembly at the transfer station at the time of preform transferinto the blow mold conveyor and immediately after, respectively,depicting a mechanical fail safe (abort) system in respectivedeactivated and the activated positions;

FIG. 9 is an enlarged view of a part of FIG. 7 showing relationship atthe transfer station of preform, outer plate of the carrier, and holderassembly;

FIG. 10 is an exploded isometric view of a section of the conveyorroller chain, holder, and guides;

FIG. 11 is a side elevation of the carriage assembly of FIGS. 7 and 8showing how a cam operates the fail safe system during thereturn-to-oven movement;

FIGS. 12 and 13 are enlarged views of the FIG. 11 fail safe clearanceplate, or inner plate, in different positions relative to the carriageouter plate;

FIG. 14 is a partly cutaway top view of the carriage of FIGS. 3, 4, and11-13 as seen on section 14--14 of FIG. 1;

FIG. 15 is a rear elevation partial section view of the carriageassembly along 15--15 of FIG. 2 showing the vertical carriage drivemeans and other features;

FIG. 16 is a partial section side elevation along 16--16 of FIG. 1showing the telescoping relation of the stuffer and center rods andalignment therewith of holder assembly, preform, and blow mold;

FIGS. 17 and 18 are enlarged views of parts of FIG. 16 emphasizing theface seal flexing of the holder into a sealing position respectively,and FIG. 18 also shows the snug fit between the holder and groove;

FIGS. 19 and 20 show the ejector workstation along 19--19 of FIG. 1before and after ejection from the holder;

FIG. 21 is a section along 21--21 of FIG. 20;

FIG. 22 is a top plan view of the roller chain along 22--22 of FIG. 1depicting, inter alia, the guide blocks straddling the lanes at thecarriage-conveyor transfer station; and

FIGS. 23 and 24 illustrate a preferred fail safe system, are respectiverear and side views comparable to FIGS. 15, 9, omit some parts forclarity, and show optional features omitted for clarity from otherFIGS., FIG. 24 being a section along 24--24 of FIG. 23.

Throughout the following description the same reference numbers are usedto refer to same parts. As already stated above, the description is madeby way of reference to the preferred application of the presentinvention to handling a preform in an RHB-V blow molding system, itbeing understood that other applications of similar shaped articles arewithin the spirit of this present invention. The present invention alsois described and illustrated for the handling of four articles at atime, it being understood that a different quantity can be handledsimultaneously and that the description usually refers to the handlingof only one for the sake of simplicity, not by way of limitation.

GENERAL DESCRIPTION (FIGS. 1, 2)

The purpose of the blow molding conveyor 1 of the present invention isto receive a preform 5 when ejected from an oven 7 in which it has beenheated and then to transport it through a series of operations whichinclude blow molding it into a bottle and ejecting it from the blowmolding machine 6. To do this, oven 7 ejects preform 5 verticallydownward into a carriage assembly (reach and take) means 9. The carriageassembly means moves the preform to where it is engaged by a conveyorsystem 10 at a transfer station 12. The conveyor system has three workstations through which it moves the preform: the aforementioned transferstation 12, a blow molding station 14 where preform 5 is blow moldedinto a product 15, normally a bottle, and then an eject station 16 wherethe preform is removed from the machine environment. The conveyor systempreferably comprises an endless conveyor member 18 having holder means20 protruding therefrom. The preform 5 is transferred from carriageassembly 9 at the transfer station 12 into one of the holders 20 andstays engaged therein from the work station through the blow molding andeject operations and stations.

Preferably, the endless conveyor member 18 which interacts with carriage9 comprises a roller chain 22 disposed with its pins 23 (FIG. 10)vertical and around sprockets 25, 26 (FIG. 22) which turn about verticalaxes.

The invention also includes an improved stuffer 27 for use at the blowstation featuring telescoping center and stuffer rods 28, 29 and a faceseal structure for interacting with the preform and the blow mold toachieve molding. Further, the invention includes a unique aspect of theejection apparatus which ejects the preform along a vertical axis,thereby providing a predetermined position as well as location below themachine where it may be received and taken away by means not part of theinstant invention.

THE PREFORM (FIGS. 2-6, 9, AND 18)

The preform 5 (FIG. 2) is of injection molded thermoplastic biaxiallyorientable material which will so orient upon being blown in a moldunder certain conditions, including preform temperature. For example,polyethylene terephthalate orients in the range from about 200° F. to250° F. Preform 5 has a hollow body 30 of circular cross-section, shapedlike a test tube with an externally threaded lip 31 above a pilfer proofring 32 which is above a support ring 33. The space between the tworings 32, 33 provides an annular groove 34 by which holder 20 engagesthe preform.

Preform 5 is not blow molded in the region of threads, groove andrings----collectively called the finish 35----hence is not heated insuch region by the oven. For this reason the preform is handled (e.g.FIG. 2) and engaged (FIG. 6) by its finish 35 until the blow molding hasbeen accomplished.

The biaxially orientable material is commonly and preferablypolyethylene terephthalate in amorphous form but may also comprise otherbiaxially orientable resin. Preform structure, materials, etc. aredescribed generally in the above mentioned U.S. Patents and elsewhere toall of which the reader is referred for additional preform information.

REACH AND TAKE OR CARRIAGE ASSEMBLY MEANS 9

(FIGS. 1, 2, 7, 8, 11-15)

The reach and take assembly 9 comprises on frame 40 a horizontalcarriage base 41 supported on guide rails 42 by means of linear bearings43 to move back and forth between oven 7 and transfer station 12 of theconveyor system. A vertical carriage assembly 45 is also mounted oncarriage base 41 and is constructed to move at proper times from a lowpreform-receiving elevation (FIGS. 2, 8) underneath oven 7 to a greaterelevation (FIG. 7) where the preform is at the correct height forreceipt and engagement by conveyor system 10 at transfer station 12.There is also an abort or fail safe means 46 (46B in FIGS. 1-15; 46A inFIG. 23, 24) associated with vertical assembly carriage 45 to insurethat no preform remains in carriage assembly 9 at the time it is movedunderneath the oven.

A rotary actuator 48 is secured to frame 40 underneath horizontalcarriage 41 which it engages by sort of scotch yoke 49 to cause the backand forth motion of the overall carriage assembly or reach and take.Scotch yoke 49 includes two spaced apart rails secured underneath base41 and within the resulting groove moves a pin or preferably camfollower 47 (FIGS. 7, 8) on the actuator crank arm. The rotary actuatoris preferably a hydraulic cylinder designed to provide 180° of crankoperation and then to reset and is commercially available.

As should be appreciated from the drawings, four preforms 5 are handledat a time, that being the quantity received simultaneously from oven 7.However, since their handling is identical in each lane, the descriptionis given for one preform only, it being understood that the system iscapable of conveying a plurality of them from the time they are receivedfrom oven 7 to the time they are ejected from the conveyor system atstation 16.

Frame 40 (see FIGS. 2, 14) is preferably an assembly rather than a solidpiece of material and includes channel end pieces 50 and I-beam sidesills 51 arranged in a rectangle with gussets 52 on the corners, amounting hinge 53 securing one end of same to the base of the blowmolding machine and a hand wheel 54 operated lock on the opposite baseend to secure as by threads 55 to the blow molding machine. Center sillchannels 57 and slats 58 provide central stiffness and a recess in whichis secured cam 59 of the fail-safe system.

A vertical cylinder mounting plate 60 is secured at right angles to base41 and reinforced in that position by gussets 62: these elements,bearings 42 and vertical guides 63 (secured to plate 60) are allincluded in the horizontal carriage assembly which in turn supportsvertical carriage assembly 45.

Vertical carriage assembly 45 includes the vertical carriage base 65 onwhich are mounted linear ball bushing bearings 66 which are guidedvertically by guides 63. An upper support ring plate 68 is fixedlysecured to the uppermost end of base 65 and has a locating means 69 onthe plate trailing edge consisting of the upwardly bent trailing portion(see FIGS. 3-6). Support ring notches 70 are cut in the upper platetrailing edge and, as seen from above (FIGS. 5, 14) are shaped like theGreek capital letter Omega (Ω) to define, in the horseshoe or U-portion,a circular sector 71 recess just slightly larger in diameter than (about0.030 inches to 0.050 inches preferably 0.040 inches) the diameter ofpreform support ring 33. The legs of the Omega (Ω)----which terminate inlocator or bent edge 69----are spaced apart sufficiently to allow thepreform body 30 readily to pass between them (about 1/16 inch to 1/8inch more than the diameter of body 30 and in FIG. 6 designated distance72).

A vertical power means that preferably is double acting air cylinderassembly (or more broadly, fluid cylinder) 75 is secured to cylinderplate 60 and its plunger or piston rod is drivingly connected tovertical carriage assembly 45, preferably as shown to base 65 by tab 76(FIGS. 7, 8). Cylinder 75 reciprocates to push the vertical assembly 45from the lower position at the oven (solid lines FIGS. 2, 8) up to thelevel of the aligns groove 35 with holder 20 (dotted FIG. 2, solid FIG.7) for transfer at station 12, respectively.

FIGS. 23, 24 illustrate optional but preferred fly bar 77 held by andbetween brackets 78 which are secured to the edges of tray 79 that inturn is secured to vertical base 65. The tray guides any preformsaccidentally hung up when they drop to a location (e.g. scrap binunderneath, not illustrated). Fly bar 77 keeps the preform lower endfrom swinging counterclockwise (FIG. 24) under inertia and mayconveniently be made of tubing.

FAIL SAFE MEANS (FIGS. 1-15, 23, 24)

FIGS. 1-15 and FIGS. 23, 24 respectively, show mechanical fail safemeans 46B and preferred power cylinder fail safe means 46A to assureremoval of an accidentally retained preform in vertical assembly 45.Both means have a reciprocatable inner plate 80 (FIGS. 3-6) mountedimmediately underneath and in sliding engagement with outer plate 69.This inner plate supports the preform by engaging the underside of thesupport ring and is withdrawn from underneath preform support ring 33(see FIGS. 12, 13) to remove such support and is likewise withdrawn toassist in removing an accidentally retained workpiece. U-shaped notches81 are in the trailing edge of plate 80 and preferably as depicted(FIGS. 5, 6) are shaped to include a semicircular end 81C with twoparallel legs 81E (FIG. 6) each tangent to the ends of the semicircle.Semicircle 81C has a diameter about 0.005-0.020 inches larger than thediameter of the preform body at that point (e.g. FIG. 6). Notch 81 hasas undercut or relief 83 to minimize the area 84 in contact with thepreform body 30, hence to reduce conductive heat transfer away from suchbody. Guide plate 85 is fixed to movably plate 80 and preferably is bentout of sheet metal to have (FIG. 4) mounting flange 85F, vertical web85D depending therefrom, and an apron 85A extending obliquely from theweb to a location under notches 81. Apron 85A has notches 88 cut thereinand shaped like the projection of notches 81 onto the slope or plane ofapron 85A. Plate 85 holds preforms in the preferred exactly verticalposture and assures preforms ejected during fail safe fall away, amongother features.

In the depicted (FIGS. 14, 15) presently preferred construction, twomirror image outer and inner plate 68, 80 are provided, one right handand left version of each and spaced apart sufficiently to provide acentral gap. Use of two short pieces of each facilitates manufacture ofa flat part, although one long piece for each may be used. Flange 85Fand web 85D of guide plate 85 extends all the way across on cross bar 89and support thereon both inner left and right hand plates 80, thusobtaining movement as one when the actuating means operates and resetsthe inner plate(s) 80.

Also, as best shown in FIGS. 12-15, the assembly of an inner plate(s) 80and guide plate 85 is movably mounted on a pair of linear ball bearings90, the bearing cage 91 (FIG. 13) of which is secured to vertical plate65 and the guide rod(s) 92 (FIG. 12) of which are secured to the 80, 85plate assembly. A snubber or shock absorber in the form of a resilientpad or washer may be provided at each end of the guide rod between theretaining nut and the bearing end.

FIGS. 23, 24 show abort cylinder 96. Cylinder 96 is mounted on or underplate 80 and its plunger 98 secured to vertical carriage plate 65 byL-shaped bracket 97. Admission of air in the left end of 96 moves oractuates cylinder 96 to reciprocate inner plate 80 from the normal orpreform support FIG. 12 position to the fail safe eject position ofFIGS. 11 and 13.

The mechanically actuated fail safe 46B depicted in FIGS. 2, 7, 8, 11-15has a linkage that is actuated by engaging cam 59 to move inner plate 80from the preform supporting position illustrated in FIGS. 3, 4, 12 tothe eject or clearing position of FIGS. 11, 13 whereby an undesirablyretained preform falls away as in FIG. 11. The linkage is a four-barcrank mechanism mounted on vertical carriage plate 65 and has a rollertype cam follower 100 supported on crank 101 which swings about a pin oraxle 102 supported from plate 65. Connecting rod 103 has respectivelower and upper clevises 105, 106 secured thereon (as by theillustrated, not numbered, known thread-and-locknut). Lower clevis 105provides the pin or pivot between crank 101, rod 103 and on which roller100 turns.

Upper clevis 106 connects by pin joint 107 to bell crank 108 which isrevolvably mounted to turn about pin 110 which is in turn supported fromplate 65 by bracket 111. Helical spring 114 is held in tension betweenpins 102 and 107--hooks on the spring ends rest in annular grooves onthe overhanging portions of the pins as is well known (FIG. 15). Tensionin this spring biases the crank mechanism in FIGS. 7 and 12, i.e. to theposition of FIGS. 3, 4 where inner plate 80 can support a preform fromthe underside of ring 33.

The other arm of bell crank 108 ultimately connects to plate 80 througha sort of scotch yoke 115, 116, 117 to allow for changing centerdistances. Thus, when reach and take assembly 9 is moved from thetransfer station 12 to the oven discharge station, follower 100 hits cam59 enroute, actuating the fail safe whereby bell crank 108 movescounterclockwise as seen in FIG. 12 to the FIG. 13 position whereuponany undesirably retained workpiece is removed. The Scotch yoke herecomprises roller cam follower 155 on the bell crank, a bracket 116secured to cross bar 89, and vertical groove 117 in the bracket in whichis received follower 115.

THE INDEXING DRIVE TRAIN (FIG. 1)

This is an assembly of commercially available items that functions toperiodically index the conveyor system (chain 18 and holders) thereby tomove a group of four preform holders successively into transfer station12, to blow station 14, then to eject station 16, and then to step thegroup back around to repeat same----all in synchronism with the oveneject and reach and take functions. It includes mounted on frame 119 anelectric motor 120 driving a clutch-brake 122 through a timing belt 123wrapped about suitable toothed pulleys. A gear reducer 125 slows downrotary speed (10:1) and feeds its output into an index drive unit 127which is commercially available from several USA sources such asFerguson Machine Company, St. Louis, Miss and/or CAMCO (Commerical CamDivision, Emerson Electric), Wheeling, Ill. Preferably a 90° dwell, 270index per 360 input is used but this does depend on original motor 120speed and overall speed reduction.

The indexing (i.e. periodical unidirectional arcuate motion) from 127output goes through suitable shafting 129 to chain drive sprocket 25.Shafting 129 is preferably an assembly with a roller bearing supportedshaft housed in a pillow block. Idler sprocket 26 (FIG. 2) isconstructed and mounted similarly on assembly 131 at the other end ofthe conveyor preferably with a chain tensioning means 133. Assemblies129, 131 and tensioner 133 are mounted on frame 119.

CONVEYOR SYSTEM 10 AND HOLDER 20

(FIGS. 1, 2, 7-9, 18, 22)

The Conveyor System 10 includes an endless conveyor member 18 (FIGS. 1,2) preferably a roller chain 22 (FIG. 10) which is wrapped in endlessfashion about sprockets 25, 26 (FIG. 2) and thus, along with other partsof the system, is mounted directly or indirectly on frame 119. Note thatmounting components on frames 40, 119, permits manufacture of theseitems of commerce and facilitates retrofitting RHB-V blow moldingmachines as well as use in other contexts in contrast to on-siteassemblage.

Chain 22 is supported with its pins 23 on vertical axes and preferablyis prestretched and is kept linear and in tension on the active side ofits path so that workstation 12, 14, 16 may be along a straight line andthe workpiece only has to travel lineraly.

Roller chain construction is well known but for background andconvenience the standard nomenclature of some FIG. 10 parts is now given(using terms from Mark's Mechanical Engineers Handbook, Fifth Ed., page925 et seq.): a pair of pin link plates 140 connect adjacent pins 23 andare disposed on the outside of the chain; about each pin is a bushing141 which preferably extends through the roller link plate 143 on theinside of the pin links 140; a roller 144 is about each bushing andspaces the pair of roller links 143.

Holder assembly 20 (FIG. 10) is attached to the chain by using anextra-long pair of pins 23X (extended pins) secured in the usual mannerto an uppermost pin link 140 and which pass through the bushings androllers to the lowermost special pin link 145 which is oversized (thatis, has an integral lug as an attachment means which extends out fromthe chain as illustrated in FIGS. 2, 10, 22) through a low friction(e.g. nylon 101) carrier guide 146 and finally through the inboard endof leaf spring 148 where a rivet head or other fastener secures alltogether. That is, extended pin 23X secures together the usual parts ofa roller chain between a pair of pin link plates and additionallysecures on the lower side carrier guide 146 and spring 148. Cap screws149 provide supplemental fastening of carrier guide 146 to lug 145 andspring 148, respectively.

Holder per se 150 comprises the above assembly 20. Holder 150 isattached by a pair of screws 152 to the outer or free end of spring 148.The holder has a U-shaped notch 154, 155, 156 of a size and thickness(FIG. 18) to snugly engage groove 35 of the preform. For examplesemicircular rear part 154 of the notch should be 0.980 inch diameterand a 0.147 inch thickness for the standard groove 35 on a standardfinish for a 28mm soft drink bottle and similarly for other sizes. Legs155 of the notch are parallel on the inside and, of course, spaced bythe aforesaid diameter. The ends 156 of the legs are tapered about 5°top and bottom.

Preform 5 is moved in a path where the flat bottom 33B of the supportring 33 clears the top of blow mold by about 0.005 inches. Thisclearance is eliminated during blowing by the stuffer nose flexingspring 148 to establish seals between 33B and the blow mold and a faceseal between nose and finish.

Carrier guide 146 is molded of low friction plastic material preferablynylon 101 and has a main body part 160 (through whcih pins 23X pass) ofthe correct thickness to provide alignment (especially vertically) atthe work stations. On opposite sides of the body are linear bearings 162which have a leader slope or taper 164 on the leading and trailingcorners. Bearings 162 slide in grooves 166 in rails 168. A pair of rails168 secured to frame 119 (FIGS. 9, 19) with the chain 22 supported inbetween by bearings 162 engagement with groove 166. The rails aredisposed (FIGS. 1, 22) along the straight runs of the chain, especiallyon the line past the workstations 12, 14, 16 and on the return run.

Referring to FIGS. 1, 2, 18, 22 means are provided to guide, urge,retain the workpiece (preform or bottle) against the curved backside 154of holders 150 thus to positively locate at predetermined positions atthe workstations. In the illustrated embodiment, preforms 5 aredelivered from the oven by carriage assembly 9 in a group of four alongfour lanes into a corresponding number and group of holders 20 attransfer station 12 (FIG. 9). A plurality of guide blocks 170 (FIG. 22)are supported by brackets 172 from frame 119 downstream of each lane sothat movement of the group of preforms from station 12 to station 14moves them past the guide blocks and guides then keeps all preformslocated against backside 154 of the holder notch. Each guide has a taper174 converging in the direction of movement (i.e. from 12 to 14) and astraight section 175 to maintain position. Guide blocks 170 arespaced--see FIG. 22--to permit the movement between them of the preformsduring the transfer from the carriage unit 9. A continuous blow moldguide rail 177 is supported at the blow station 14 by bracket 178 tomaintain preforms location there for the blowing function (FIG. 16-18).

Preferably the sprockets are of equal size and the side of the chain intension runs past the work stations 12, 14, 16 which latter are spacedoutward from the chain sufficiently to align correctly with proforms inthe holder 20 notches. The holders in turn are arranged in groups (shownas four) corresponding to the number of blow molds and spaced within thegroup the same as such molds. The groups, rather corresponding holdersin successive groups are spaced the amount the chain moves on eachiteration, which is usually greater than the spacing between holders ina group.

STUFFER 27 (FIGS. 1, 16, 17)

In blow molding of plastic bottles, stuffer is the common term for adevice to connect a preform to a source of air for blowing. The priorart for an RHB-V used a yoke to raise and lower all the stuffers at onceand inserted a male element into the finsish 35. The present inventionhas a face seal to the finish and also has independent movement of thestuffer 27 for each preform with a novel telescoping relation betweenstuffer rod (and nose mounted on it) and the center rod 28 where thelatter, as an option, is provided.

As shown in FIG. 1, the stuffer assembly 16 is mounted at the blowmolding station on a frame having an upper cross piece 180 on which ismounted the center rod cylinder and a lower cross piece 182 secured totheir frame 119 and on which are supported the stuffer cylinders 185.All of these are vertically aligned to be substantially coaxial with theblow mold 188 associated with each stuffer and center rod unit.

Both the center rod cylinder 190 and stuffer cylinder assembly 27 aredouble acting and preferably are pneumatic rather than hydraulic inorder to keep air above the molds and parts handling the preform. Use ofair above, as is well known in the art, reduces or eliminates problemsassociated with hydraulic oil systems such as leaks, contamination ofthe product, misting etc.

Stuffer cylinder assembly 27 has a hollow double ended plunger 29mounted on the piston 192, each end of plunger 29 protruding from itsrespective end of the cylinder past an air seal 194. This plunger ishollow, having a bore 196 that is big enough to permit the center rod 28to pass completely therethrough and to operate in telescoping relation.On the bottom end of the stuffer assembly is a stuffer nose 198 having alongitudinal bore 200 coaxial with and substantially the same size asthe bore 196 through the plunger. A seal 202 to avoid air leaks isprovided at the upper end of nose bore 200 to prevent leakage ofcompressed air past the center rod. Air as seen in FIGS. 16, 17 isbrought from a source through a passage 204 in the wall of the stuffernose into the nose bore.

At the lowermost end of nose 198 is face sealing surface 206 whichestablishes a face seal with the top of the preform 5. Enough pressureis applied to the upper cylinder to maintain this face seal against thepressure of blow air passing into the hollow part of the preform fromthe stuffer nose bore.

As shown in FIGS. 16, 17, 18 when the system is in a blowing mode withair entering through the stuffer nose bore, the leaf spring 148 ofholder assembly 20 is flexed slightly to permit the sealing of the ring33 against the top of the blow mold. The leaf spring flexes rather thanrequiring substantial deflection of roller chain 22 which later would beundesirable because it would be in the direction of the pin 23 axes.

EJECTOR 16 (FIGS. 19, 20, 21, 22)

The ejector station 16 is where double acting air cylinder 210 pushesthe now blown bottles out of the open end of the notches 154-156 to alocation where they can fall away. In the preferred embodiment, aplurality of vertical guides are provided so that the bottle falls awaywhile being maintained in a vertical orientation.

FIGS. 19-22 illustrate the ejector air cylinder 210 with a pusher bar212 on the end of its plunger 214. This pusher bar extends in thedirection along the roller chain and is long enough to contact all ofthe now-blown bottles 15 at once during the ejection mold. The pusherbar being so long, one or more guide rods 217 are attached to it and fitin a linear bearing 220 supported on conveyor frame 119.

As best seen in FIG. 21, each bottle is pushed out of its holder notchagainst a fixed vertical guide bar 223 which depends from the frame 119,and being connected thereto by a suitably sized cantilever bracket 224.The face of this bar is coated with a very low friction wearing surface225 preferably Teflon tape or a coating of a similar material.

Movable guide rods 226 depend vertically from the bottom of the pusherbar, two for each station and engage the bottle body. The movable guiderods do not engage the bottle until about the time pusher bar 212engages the finish during the ejection function. The pusher bar 212 isshaped to over-reach the top of the bottle (FIGS. 19, 20) so that it canengage the finish support ring 33 to push the bottle all the way upagainst fixed guide rod 223 and at the same time bring depending guiderods 226 into engagement with the bottle body as illustrated in FIGS.20, 21.

The timing of this cylinder and eject operation is such that bottle 15begins to descend vertically while engaged between all three of theguide rods 223, 226 and has just about completed its descent when thecylinder 210 retracts the pusher bar 212 and moving guides 226 dependingfrom it.

REVIEW OF MACHINE OPERATION

As mentioned in the section subtitled "General Description", the purposeof this invention to receive the preform in the carriage assembly 9 atoven 7, place it in the conveyor assembly 10 at transfer station 12 andthen to move it through a blow molding operation at 14 and the ejectstation 16 where it leaves the machine as a finished product. Operationis understood by following a workpiece (initially a preform) through themachine referring to key machine elements now identified. Understandthat preferably a plurality of workpieces, starting as preforms 5,usually four, are processed through the machine simultaneously.

The oven 7 indexes and stops with a preform hanging vertically ready tobe discharged. At this point in time the carriage assembly 9 moves thenotches 70, 81 vertically by means well known (e.g., the aforesaidpatents) discharges the preform vertically down and into the notch whereit is received and cause to self-center by reason of the relative sizeof notches 70, 81 and the bent trailing edge 69. The rotary actuator 48now begins to swing its arm 180° to drive the carriage assembly and thepreforms therein to transfer station 12. While this motion is takingplace, the vertical carriage cylinder 75 is triggered and pushes orextends vertical carriage assembly 45 from its lower most positionillustrated in FIG. 2. to its upper most position illustrated in FIG. 7,15 (and phantom FIG. 2), thus adjusting the height to the correct levelfor transfer to the conveyor assembly at workstation 12.

As the rotary actuator completes driving the carriage assembly 9 all theway to the left as seen in FIG. 2, 7, preform groove 35 is engaged bynotch 154-155-156 in the holder 20 as the carriage assembly moves or isswept underneath conveyor assembly 10. Thus, the preforms are literallyswept free and clear of the carriage assembly and simultaneously engagedin the notch of the conveyor assembly holder.

At this point, vertical carriage cylinder 75 operates again to retreat,i.e. to pull carriage notches 154-156 down to portions of the preformand eliminating the probability of catching a preform in the carriagenotches--or more correctly in plates 68, 80 or vertical plate 60 whenthe conveyor actuates to transfer preforms from station 12 to the nextworkstation. With the carriage pulled down to the FIG. 8 compressedposition, the rotary actuator operates in the opposite direction toreturn the carriage assembly to the oven discharge for a repeat of theabove events. This operation preferably takes place concurrently withoperation of the conveyor assembly to transfer the workpiece through thework stations. However, during the return of the carriage to the ovendischarge, the fail safe or abort system is actuated to insure clearingaway any accidentially retained workpiece.

In the embodiment of FIGS. 2, 7, 8 cam follwer 100 hits cam 59 duringthis return stroke and actuates the four bar linkage to turn bell crank108 and reciprocate inner plate 80 as in FIGS. 11, 12, 13. Asexemplified in FIG. 11, this would clear away any preform accidentallyretained.

In the preferred embodiment of FIGS. 23, 24 fail safe air cylinder 96 isactuated manually or in response to limit switch or sensor valveactuation to directly move the inner plate 80 back and forth to move thesupport 81, 83 from any retained preforms and then to reset the same.

The respective fail safe functions are completed by the time thecarriage assembly is returned to the position of FIG. 2 where it isagain ready to receive the next (batch of) preform(s) delivered fromoven 7.

In the meantime, conveyor assembly 10 is actuated by the indexing drivesystem 120-127 of FIG. 1 to move the group of preforms just received atwork station 12 to blow molding station 14, stopping in a correct andsubstantially coaxial alignment with the center line of the stufferassembly and center rods 27, 28 located at that station. When thisoperation takes place, each preform 5 that has been located at blowstation 14 has been converted to a bottle 15 (if the blow moldingoperation were successful) and the group is moved to the eject station16. In the meantime, the following group of preform holders 20 is movedinto position at transfer station 12 sliding on supports 162 andpreforms guided means 170 where the above operations coordinating withthe carriage assembly can be repeated at the correct time and the holdergroup ahead of the eject station move on around one interval each.

Once the preform 5 is located at blow station 14, the blow mold(s) 188is/are closed, the stuffer assembly 27 operates and stuffer nose 198engages the preform to create the face seal described in more detailwith reference to FIGS. 18-22 and the system is now ready to blow mold abottle by introducing air through the stuffer nose bore 200. If centerrods 28 are provided (this is an option not all machines have), thecenter rod cylinders 190 are actuated by providing compressed air todrive center rods 28 down sufficiently fast to follow the preform to thebottom of the blow mold in a manner known in the art.

When the blow molding operation is completed the center rods 28 areretracted upwardly into the nose and the nose is, of course, retractedto eliminate the face seal and release compressed air within the nowblown bottle 15, returning to the positions approximately illustrated inFIG. 1.

While the blow molding operation is taking place at station 14, an ejectoperation is taking place at station 16 by applying compressed air tothe rear end of the cylinder 210 causing it to move the push bar outagainst the workpiece----now a bottle finish----and the movabledepending guides 226 against the body of bottle 15. This moves thebottles out of the holder 20 notch 154 against the fixed vertical guidebar and the bottles then begins to fall away and continue to do so. Theejector cylinder assembly then resets.

Operations of a system as above on an RHB-V machine successfully blewfour two liter bottles about every 2.3 seconds, the so-called cycletime. When dry cycling (i.e. no preforms or blowing) the machine can bespeeded up to about 2.1 second cycle time. Cylce time when blowing islimited by the blowing and cooling time at the blow station.

Once the blow molding and eject functions have taken place (and they areboth done at the same time on different groups), the blow molds areopened and the system is now ready to be indexed once more to repeat theforegoing.

What is claimed is:
 1. An improved stuffer apparatus for use in blowmolding a plastic bottle within a blow mold from a plastic preform andcomprising:a stuffer cylinder having a hollow plunger with a first boreextending completely therethrough; a stuffer nose secured on an end ofsaid hollow plunger, having a nose sealing structure for establishing anair tight seal with the preform, and haviong a nose bore extendingcoaxially from said first bore to and thru said sealing structure; along stroke center rod cylinder mounted vertically above and coaxialwith said stuffer cylinder, having a centering plunger that extends whenfully retracted through all of the above bores to about a remotest partof said nose sealing structure; and having a stroke large enough to movean outboard end of said centering plunger from said fully retractedposition to engagement with a bottom of the preform being blown when atthe blow mold bottom; and blow air passage means in said nose forconveying blow air through the nose to an exit into the preform at saidnose sealing structure.
 2. An improved stuffer apparatus according toclaim 1 further comprising:said air passage including an enlarged partat the end of said nose bore surrounding said centering plunger whichpart is located to exit into the preform being blown; and air seal meansproviding a sliding seal against air leaks between said centeringplunger and at least one of said bores.
 3. An improved stuffer apparatusaccording to claim 1 further comprising:said nose sealing structurecomprises a face seal which achieves an air tight seal by compressionagainst the preform.
 4. An improved stuffer apparatus for use in blowmolding a plastic bottle within a blow mold from a plastic preform andcomprising:a stuffer cylinder having a hollow plunger with a first boreextending completely therethrough; a stuffer nose secured on an end ofsaid hollow plunger, having a nose sealing structure for establishing anair tight seal with the preform, and having a nose bore extendingcoaxially from said first bore to and thru said sealing structure; andblow air passage means in said nose for conveying blow air through thenose to an exit into the preform at said nose sealing structure.
 5. Animproved stuffer assembly apparatus for a blow molding machinecomprising:a stuffer frame supported above the blow molds of suchmachine; a plurality of double acting long stroke fluid cylinderssupported on an uppermost part of said frame each with a plungersubstantially vertical and coaxial with the longitudinal axis of apreform to be blown; a corresponding plurality of double acting shortstroke stuffer cylinders each being supported and located below acorresponding one of said long stroke cylinders for a vertical stroke;each having a hollow plunger with a center rod bore extending completelythrough it and that receives a corresponding center rod plunger in thehollow portion thereof; a stuffer nose on the lower end of each saidstuffer cylinder plunger with a generally central bore aligned with itscorresponding center rod bore; a seal surface on the lower end of saidstuffer nose for sealingly engaging a preform during blowing, saidstuffer bore passing thru said seal surface for communication with theinterior of a preform to be blown; said stuffer bore having an enlargedlower end, the stuffer bore passing thru the seal surface as above; aninlet air passage through an intermediate part of said stuffer nose intosaid enlarged bore lower end; said center rod plunger extending intelescoping manner through said stuffer cylinder and its center rod boreand through said stuffer nose and its central bore and the enlargedlower end and having a stroke sufficient to move its lower end to thebottom of a workpiece when in the blow mold; and a seal between thecenter rod plunger and said central bore above each inlet air passage.